How to stop some one signing in to my hotmail from different location when my password is saved ther

Hi All. I recently lost my mobile phone. On that phone I was using opera mini browser and I put hotmail to be automatically sign in and saved my password. Every time I launch opera mini browser and click hotmail (saved in bookmarks) I was automatically signing in. Now I have lost that phone and I wonder if some one finds that phone and starts opera mini browser and click on hotmail he will be signing in to my hotmail and can read or delete my emails. I have already changed my password but I checked on new phone that if I am signing in automatically on phone and even after changing password from my computer it still signs in from mobile (from old saved password) so changing password is not helpful now. Can some body help me please, how can I stop some one who has got my phone to stop signing in to hotmail. Many thanks.